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My Book

Warned by relatives that knuckle cracking causes arthritis, Donald Unger decided to crack only the knuckles of his left hand. For 50 years he frequently cracked his left hand, never his right. Finally he wrote a letter to a scientific journal (in which he calls himself “the author”) pointing out that he did not have arthritis in either hand, supporting the conclusion of another study which studied a much smaller amount of knuckle cracking.

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on Thursday, August 30th, 2012 at 5:00 am and is filed under personal science, self-experimentation.
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8 Responses to “50 Years of Knuckle Cracking Did Not Produce Arthritis”

Unger’s letter is light-hearted and whimsical (“spinach-eating”!) and the authors of the previous study answered in kind. So in a way it is a joke, on both their parts. More like a case study so of course it’s statistically ‘underpowered’.

Seth: “Joke” usually means “didn’t actually happen” (“I was joking!”). I see nothing to suggest that what Unger described didn’t actually happen. In fact, I believe Unger — like most of us — is not creative enough to make such stuff up.

You’re right. I don’t know whether the 50-year “self-controlled study” actually happened or not. It’s certainly not impossible but fifty years of one-sided knuckle cracking seemed unlikely to me. The letter and response read like satire to me. The response is certainly satire, especially the “statistical analysis” of Dr. John Adams, e.g., “Typically, sample sizes of roughly twice the available research budget are required for valid inference.” (Not seeing a journal name at the top or bottom of either page also made me suspicious.)

If I had access to a medical library, I would see if the cited 1973 article actually exists (I’m so ignorant I don’t even know if there was a Western Journal of Medicine in 1973). If I was a hot shot Berkeley Psychology Professor, I’d call Dr. Unger and ask him personally whether the letter described something that had actually happened or was “a joke.”